Buffing device for railway switches and the like



Aug. 2, 1932f w. c, MGWHIRTER. 1,869,504

BUFFING lDEVICE FOR RAILWAY SWITCHES AND THE LIKEl original Filed sepan, 1929 2 sheets-sheet l1 Aug. 2, 1.932., w. c. MQWHIIRTER* v 1,869,604

AvBUFFING DEVICE FOR RAILWAY SWITCHES AND THE LIKE Original Filed Sept. 11, 1929 2 SheetS-Sheet- 2 D n f No *g tog I l@ ll l ,miv wr.. l Svp "S3" QU, N EW v .N

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v a N u glu (o e m E 1 e N e@ It?) w l@ NND cf mi@ I in GDN @Own INVENTORZ W C. /"7al///ufr-lL-rl @im Patented Aug. 2, 1932 PATEN orrics WILLIAM C. MCWHIRTER, OF WILKINSB'URG, PENNSYLVANIA, ASSIGNOR TO THE UNION SWITCH &; PENNSYLVANIA SIGNAL COMPANY, OF SWISSVALE, PENNSYLVANIA, A CORPORATION OF BUFFING- DEVICE FOR RAILWAY SWITCHES AND THE LIKE Application led September 11, 1929, Serial No. 391,801. Renewed April 14, 1932.

My invention relates to bufling devices for railway switches and the like, and has for an object the provision of a bufling device for a spring switch which will permit free movement of the switch from one extreme position to the other by a switch operating device, and which will permit the switch points to be fully moved away from either eXtreme position by a trailing railway vehicle, but which will retard the return of the switch points to their initial. positions after such vehicle has trailed through the switch.

I will describe one form of buffing device embodying my invention, and will then point out the novel features thereof in claims.

In the accompanying drawings, Fig. 1 is a top plan view, partly cross sectioned, showing a spring switch provided with one form of buffing device embodying my invention. Fig. 2 is an enlarged right hand end view of the buiiing device shown in Fig. 1. Fig. 3 is an enlarged sectional view on the line III-Ill of Fig. 1. Fig. 4 is a sectional view on the line IV-IV of Fig. 2, and Fig. 5 is a sectional view on the line V-V of Fig. 2.

Similar reference characters refer to similar parts in each of the several views.

Referring first to Fig. 1, the reference character A designates a railway switch, and the reference character B designates a device for operating it. The switch A comprises, as usual, two fixed rails 1 and 1a, and two mov able switch points 2 and 2a, the switch points being connected together near their tips by 24 a front rod 3.

The operating device B, as here shown, comprises a switch stand 4 having its base 4a spiked or otherwise secured to the ties adjacent the switch A. A gear shaft 6 is journaled in the switch stand 4 and carries a crank 5, and a gear segment 7. The gear segment 7 meshes with a bevel pinion 8 keyed to a pinion shaft 9. rlhe pinion shaft 9 extends through the side of the switch stand 4 and "-'has attached to its outer end the usual weighted switch throwing lever 10.

The crank 5 of the switch throwing device B is connected with the front rod 3 of switch A by means of a link 11 and a spring conf necting rod C. The sprinU connecting rod C may have any suitable form, but in the well known form here shown, this connecting rod comprises a cylindrical housing 14 having a lateral extension 14a fastened to the front rod 3. The right hand end 14b of the housing 14 has a smaller diameter thanthe body of the housing, while the left hand end is threaded to receive a cap 15 having an end 15a similar to the end 14h. Slidably mounted in the opening in the end 14b is a sleeve 16 pro-vided with an annular flange 16L located within the housing 14, and similarly mounted in the opening in the end 15a is a sleeve 17 provided with an annular fiange 17a, located within the housing 14. A spring rod 12 extends through both sleeves 16 and 17 with sufficient clearance to permit the rod to slide freely in the sleeves, and this rod carries a compression spring 78 which engages the sleeves at the annular fianges and urges the sleeves toward the positions in which the annular flange 16a of the sleeve 16 engages the shoulder formedron the inside of the housing 14 by the end 14h, and the annular flange 17a of the sleeve 17 engages the shoulder formed on the inside of the cap 15 by the end 15a. The spring rod 12 is provided with an annular shoulder 13 for at times engaging the outer end of the sleeve 16, and with a nut 18 for at times engaging the outer end of-the sleeve 17. The right hand end of the spring rod 12 is pivotally attached to the link 11.

The apparatus thus far described is well known in the art and its operation will be readily understood from an inspection of the drawings.

The front rod 3 is also connected by means of an adjustable link 21 with the piston rod 31 of a buliing device D. The buifing device D in the form here shown comprises a casing 23 provided with two integral trunnions 77 and 7 7 a (see Figs. 2 and 3) by means of which the buffing device may be pivotally supported in any suitable manner. As here shown, the bufling device is pivotally supported between two brackets 22 and 22'nl which are provided with suitable holes to receive the trunnions 77 and 7 7, respectively, and which are fastened to the ties adjacent the switch A, as best seen in Fig. 1.

Extending through the lower part of the easing 23, as best seen in Figs. 3 and 4, is a cylinder 23L which is closed at one end by a cylinder head 26 bolted to the casing 23 by means of bolts 28, and at the other end by a cylinder head 27 bolted to the casing 23 by means of bolts 29. The piston rod 3l extends into the cylinder 23SL through a stuiiing box 30 and through a suitable opening 27 a in the cylinder head 27, and is fastened t0 two spaced reciprocable pistons 24 and 25. rlhe cylinder 23aL is intended to be filled with a. suitable iiuid such as oil, and the stuiiing box 30 forms a Huid-tight joint through which the piston rod may slide.

The cylinder' wall is provided at its left hand end with a leak groove 23C and at its right hand end with asimilar leak groove 23d. The function of the grooves 23c and 23d is to permit fluid to flow past the pistons under certain conditions as will be made clear hereinafter.

The upper part of the casing 23 has formed therein a reservoir 23b (see Figs. 3, 4 and 5), which may also be filled with fluid. The cylinder 23al is constantly connected, near its center, with this reservoir by means of an opening 33 in the cylinder wall. As shown in Fig. 4, the left hand end of the cylinder 23al is connected with this reservoir thro-ugh a port 68, a regulating valve 58, and two ports 69 and 70. The regulating valve 58 may have any suitable form, but in the form here shown, i this valve comprises a cylindrical valve member 58b fitting within a hole 6l in the cylinder head 26, and attached to a valve stem 58a. The valve member 58b is provided with a plurality of restricted orifices 58C, one

. or more of which may be brought into registration with the port 69 by turning the valve member 58h. To facilitate turning the valve member 58h, the valve stem 58a is provided in its upper end with a saw kerf 58d adapted to receive the end of a screwdriver. The valve 58 is held in place by a gland 59 which surrounds the valve stem 58a, and which is fastened to the cylinder head 26 by means of two stud bolts 62 which passA through suitable holes in the gland and which are screwed into threaded holes (not shown) in the cylinder head 26. Suitable packing is inserted between the gland 59 and the shoulder formed at the top of the valve member 58b to prevent fluid from leaking past the valve.

The left hand end of cylinder 23a is also connected with the reservoir 23b through two coaxial ports 34 and 35, as best seen in Fig. 5. The How of iuid through these ports is controlled by a poppet valve F comprising a valve member 36, carried by a valve stem 37, and cooperating` with a valve seat 34El formed in the end of the port 34. The right hand end of the valve stem 37 is iuted and extends into the ports 34 and 35, while the left hand end of the valve stem 37 slides in a guide bearing 39 formed in a plug 40 screwed into a threaded opening in the cylinder head 26. A spring 38 having one end located in an annular recess 41 in the plug 40, to center the spring with respect to the valve stem 37, engages the valve member 36 and constantly urges the valve member towards the valve seat 34a.

The right hand end of the cylinder 23;l is connected with the reservoir 23b through a port 7l, a regulating valve 63, and two ports 72 and 73 (see Fig. 4). The regulating valve 63 is similar to the regulating valve 58, and comprises a. cylindrical valve member 63b fitting' in a hole 67 in the cylinder head 27 and attached to a valve stem 63a. The valve mem`v ber 63b is provided with a. plurality of restricted orifices 63", one or more of which may be brought into registration with the port 72 by turning the valve member 63". The upper end of the valve stem 63a is provided with a saw kerf 63d. A gland 64 surrounds the valve stem 63a and is fastened to the cylinder head 27 by means of stud bolts 66, packing being inserted between the gland and the shoulder' formed at the upper part of the valve member 63 to prevent ud from leaking past the valve.

The right hand end of the cylinder 23n is also connected with the reservoir 23b through two coaxial ports 42 and 43. The fiow of fluid through these ports is controlled by a poppet valve G similar to the poppet valve Ff described hereinbefore. As here shown, the poppet valve G comprises a valve member 44 carried by a valve stem 45 and co-operating with a valve seat 43L formed in the end of the port 42. rEhe left hand end of the valve stem 45 is fluted and extends into the ports 42 and 43, while the right hand end of the valve stem 45 is adapted to slide in a guide bearing 47 formed in a plug 48. The plug 48 also has formed therein an annular recess 49 which receives one end of a. coil spring 46. The other end of the coil spring 46 engages the valve member 44 and constantly urges the valve member 44 towards the valve scat 43a.

The valves F and G are operated by two tappets 53 and 54, respectively, which, in turn, are actuated by a` cam 5OfL formed by cutting away a portion of a cam, shaft 50, as best seen in Figs 3 and 5. The tappet 53 is slidably mounted in two lugs 55 projecting upwardly from the wall of the cylinder 23a into the reservoir 23h, and the tappet 54 is similarly mounted in two similar lugs 56. The cam shaft 50 is `iournaled in two bearings 5l and 52 screwed into the upper part of the casing 23 as best seen in Fig. 3. The outer ends of the cam shaft 50 are provided with threaded holes 50b and 50c into the most convenient one of which may be screwed a crank arm for operating the cam shaft. As here shown, a crank arm 57 is screwed into the hole 50C and the free end of this arm is pivotally connected with one end of an adjustable operating rod 20, the other end of which is connected with the spring rod l2 by means of a screw jaw 19. The parts are so proportioned that when switch A occupies its normal position, in which position it is illustrated in the drawings, the cam 50a is rotated out of engagement with the tappet 53 and into engagement with the tappet 54 so that valve F is closed and valve G is open. When switch A occupies its reverse position, however, the cam 50a is rotated out of engagement with the tappet 54 and into engagement with the tappe-t 53 so that valve F is opened and valve G is closed.

To facilitate the insertion or" fluid into the cylinder 23a and the reservoir 231, a screw plug 76 is provided in the trunnion 77 as best seen in Fig. 3.

The operation or" the apparatus as a whole is as follows: lVhen switch A occupies its normal position in which position it is illustrated in Fig. l, the parts of bufling device D are in the positions shown in Figs. 4 and 5; that is, valve F is closed, valve G is open, and pistons 24 and 25 occupy their extreme left hand positions. If, now, switch A is moved from its normal to its reverse position by switch operating device B, pistons 24 and 25 of buffing device D are moved toward the right a corresponding amount, and cam 50"L is rotated in a counter-clockwise direction. The construction of cam 50a is such that during this movement of the switch, valve G of buffing device D is held open until after piston 25 has moved past the left hand end of leak groove 23d, and valve F is opened as soon as piston 24 has reached the right hand end of leak groove 23C. As a result, during this movement fluid flows from cylinder 23 on the right hand side of piston 25 past valve G into reservoir 23h, until piston 25 passes the left hand end of leak groove 23d (see Fig. 5), whereupon valve G closes, and fluid on the right hand side of piston 25 thereafter flows through leak groove 23d into cylinder betweenpistons 24 and25. During this movement, fiuid also flows from cylinder 23a between pistons 24 and 25 through leak groove 23c into cylinder 23a on the left hand side of piston 24 until piston 24 passes the right hand end of leak groove 23C, whereupon valve 'F opens and fluid then flows from reservoir 23b into cylinder 23a on the left hand side ot piston 2li-through 'valve F. It will he apparent, therefore, that during the movement of the switch A from its normal to its reverse position bv the switch operating vdevice B, the fluid in cylinder 23il offers very little resistance to the movement of the pistons 24 and 25, and the buffing device D therefore exerts practically no buffing action on the switch points.

If', when switch A occupies its reverse p0- sition, the switch is returned to its normal position by switch operating device B, the operation of the buffing device D is just the reverse of that described above, and will be readily understood from an inspection of' the drawings.

lf a vehicle trails through the switch when the switch occupies its normal position, the switch points are moved toward the right as viewed in Fig. l, by the wheels of the vehicle. Under these conditions spring rod l2 of' connecting rod C is held stationary by switch operating device B, so that spring 78 of spring connecting rod C becomes compressed and exerts a force on the switch points tending to return the switch points to their initial positions. When the switch points move toward the right, the pistons 24 and 25 of bulfing device D are moved toward the right a like amount. Since spring rod 12 is held stationary, valve G of buffing device D remains open during this movement. The fluid in cylinder 23a on the right hand side of piston 25 therefore flows throughvalve G iii? into reservoir 23b until piston 25 has moved past the end of leak groove 23d, whereupon fluid then also fiows past piston 25 through this leak groove. rlfhe fluid in cylinder 23a on the right hand side of piston 24, during this movement, flows through leak groove 23C past piston 24 into cylinder 23a on the left yhand side of piston 24 until piston 24 has moved to the end of this groove, whereuponv Y the pressure of the fluid. in reservoir 23b opens valve F and permits fluid to flow through ports 35 and 34 into cylinder 23a on the left hand side of piston 24. The pressure exerted on valve member 36 of valve F by spring 38 is comparatively small, so that very little pressure is required to open valve F. It will be apparent, therefore, that the bufling device D offers very little resistance to the movement of the switch points away from their initial position under these conditions. As soon as the switch points startte return to their initial position due to the bias of spring 78, however, spring 38 closes valve F, so that fluid can not pass this valve and the return movement of the switch points is then limited "y to the rate at which the fluid in cylinder 23a on the left hand side of piston 24'can flow through regulating valve 58, until piston 24 has moved past the end of leak groove 23.

This rate may be varied by varying the number of orifices 58c which are in registration with port 69, and this rat-e is usually adjusted to such a value that the switch points will not return to their initial positions until a time interval has elapsed which is longer than i the time interval required for adjacent trucks of a vehicle to pass the switch points when the vehicle is moving at its usual speed.

When the switch occupies its reverse position, valve F is open and valve G is closed.

If a vehicle trails through the switch under the conditions, the switch points are moved to the left, but the pistons 24 and 25 are free to move toward the left and the buliing l device D therefore olfers practically no opposition to the movement of the switch points. But valve G is closed, when the switch points startto return toward their initial positions, the fluid in cylinder 23 on the right hand side of the piston Q5 is forced through the regulating valve 63, thereby retarding this movement to the rate at which fluid can flow through this valve. This rate may be varied by adjusting valve 63 as will be readily understood.

It will be apparent, therefore, that with apparatus embodying my invention substantially no opposition is offered by the bufiing device to normal manual operation of the switch, or to movement of the switch points away from either extreme position by a trailing railway vehicle, but the return movement of the points after a trailing move is retarded to a degree which can be accurately controlled by valves 63 and 58.

It should be pointed out that, while I have illustrated my invent-ion as applied toa railway switch, my invention is not limited to this use, but may be applied to any reciprocable device where similar' bufiing action is desired.

Although I have herein shown and described only one form of buffing device embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appendcd claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

l. In combination with a cylinder containing a fluid, a piston reciprocable in said cylinder, a reservoir, means including a restricted orifice for constantly connecting said cylinder with said reservoir, a cam, and a valve operated by said cam fo at times providing an additional path between said cylinder and said reservoir to vary the opposition offered by said fluid to movements of the piston in one direction.

2. In combination with a cylinder containing a fluid, a piston reciprocable in said cylinder, a reservoir, means including a restricted orifice for constantly connecting said cylinder with said reservoir, a cam operable between two eXtreme positions, a valve operated by said cam in such manner that said valve is opened when said cam occupies one extreme position but that said valve is closed when said cam occupies said other extreme position, and means including said valve for at times connecting said cylinder with said reservoir to vary the opposition offered by said fluid to movements of the piston in one direction.

3. In combination with a cylinder containing a fluid, a piston reciprocable in said cylinder, means for permitting fluid to flow past said piston for a portion of its stroke, a reservoir, means including a restricted orifice for constantly connecting said cylinder with said reservoir, a cam, and a valve operated by said cam for at times providing an additional pat-h between said cylinder and said reservoir to vary the opposition offered by said fluid to movements of the piston in one direction.

4. In combination with a cylinder containing a fluid, two spaced pistons in said cylinder rigidly fastened together and reciprocable between two eXtreme positions, a reservoir, means including a first restricted orifice for constantly connecting one end of said cylinder with said reservoir, means including a second restricted orifice for constantly connecting the other end of said cylinder with said reservoir, a cam movable between two extreme positions, a first valve controlled by said cam in such manner that said valve is opened when said cam is moved to one eX- treme position for at times providing an additio-nal path between said one of end of said cylinder and said reservoir to vary the oppostion ofi'ered by said fluid to movements of said pistons in one direction, and a second valve controlled by said cam in such manner that said valve is opened when said cam is moved to the other extreme position for at times providing an additional path between said other end of said cylinder and said reservoir to vary the opposition offered by said fluid to movements of said pistons in the other' direction.

In combination with a cylinder containing -a fluid, two spaced pistons in said cylinder rigidly fastened together and reciprocable between two extreme positions, a reservoir, means at one end of said cylinder for ,ermitting fluid to leak past one said piston for a portion of its stroke, means at the other end of said cylinder for permitting fluid to leak past the other said piston for a portion of its stroke, a reservoir, means for constantly connecting said cylinder between said pistons with said reservoir, means including a first restricted orifice for constantly connecting one end of said cylinder with said reservoir, means including a second restricted orifice for constantly connecting the other end of said cylinder with said reservoir, a cam movable between two eXtreme positions, a first valve for at times providing an additional path between one end of said cylinder and said reservoir to vary the opposition offered by said fluid to movements of the one piston in one direction, a second valve for at times providing an additional path between the other end of said cylinder and said reservoir to vary the opposition offered by said fluid to movements of the other piston in one direction, said first and second valves being operated by said cam in such manner that said first valve is open and said second valve is closed when said cam occupies said one extreme position but that said first valve is closed and said second valve is open when said cam occupies said other extreme position.

6. In combination with a cylinder containing a fluid, a piston reciprocable in said cylinder, la reservoir, means including a regulating valve for constantly connecting said cylinder with said reservoir, a cam, and a poppet valve operated by said cam for at times providing an additional path between said cylinder and said reservoir to vary the opposition oered by said fluid to movements of the piston in one direction.

7 In combination, a casing provided with a reservoir and a cylinder containing a fluid, two cylinder heads one attached to said casing at each end of said cylinder for closing said cylinder, two spaced pistons in said cylinder reciprocable between two eXtreme positions, a piston rod extending through one of said cylinder heads and attached to both said pistons for reciprocating said pistons, said cylinder being provided with leak grooves to permit fluid to flow around one piston during a portion of the stroke of said rod and around the other piston during a different portion of the stroke of said rod, means for constantly connecting said cylinder between said pistons with said reservoir, a first regulating valve in one said cylinder head, means including said first regulating valve for constantly connecting said reservoir with one end of said cylinder, a first poppet valve, a fluid path around said first regulating valve including said first poppet valve, a second regulating valve in the other said cylinder head, means including said second regulating valve for constantly connecting said reservoir with the other end of said cylinder, a second poppet valve, a fluid path around said second regulating valve including said second poppet valve, a cam shaft mounted in said casing and rotatable between two eX- treme positions, and a cam integral with said cam shaft and operating to open said first poppet valve and close said second poppet valve when said cam shaft occupies one eX- treme position but to open said second poppet valve and to close said first poppet valve when said cam shaft occupies the other eX- treme position.

In testimony whereof I ax my signature.

WILLIAM C. MCWHIRTER. 

